661621412 has 6 divisors (see below), whose sum is σ = 1157837478. Its totient is φ = 330810704.

The previous prime is 661621403. The next prime is 661621423. The reversal of 661621412 is 214126166.

It can be written as a sum of positive squares in only one way, i.e., 637865536 + 23755876 = 25256^2 + 4874^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82702673 + ... + 82702680.

It is an arithmetic number, because the mean of its divisors is an integer number (192972913).

Almost surely, 2^661621412 is an apocalyptic number.

It is an amenable number.

661621412 is a deficient number, since it is larger than the sum of its proper divisors (496216066).

661621412 is a wasteful number, since it uses less digits than its factorization.

661621412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165405357 (or 165405355 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 661621412 is about 25722.0024881423. The cubic root of 661621412 is about 871.3711641275.

Adding to 661621412 its reverse (214126166), we get a palindrome (875747578).

The spelling of 661621412 in words is "six hundred sixty-one million, six hundred twenty-one thousand, four hundred twelve".